Effect of MAP on physico-chemical characteristics of shell hen eggs

The aim of this study was to compare some physico-chemical properties (weight loss, pH, Haugh unit, gel hardenss and foam drainage) of non packed eggs and eggs packed in high barrier plastic pouches with three atmospheres (air, 100% N-2, 100% CO2) during 28 days of storage at 25 degrees C. MAP permitted a strong reduction of the weight loss from the product. While the greatest quality decline was observed for the control, eggs packed in CO2 maintained the initial values of Haugh unit during storage and the albumen pH was about 2 points lower than the control. Gel hardness showed a strict correlation with raw albumen pH and CO2 MAP caused the formation of a soft and puffy coagulum. In terms of liquid drainage, foam stability decreased during storage for all samples but eggs packed in 100% CO2 showed a more stable foam compared with fresh eggs until the fourth day. These findings suggest that the exposition of fresh eggs to CO2 enriched atmospheres could be apply as a natural method to modulate albumen pH and indirectly the rheological properties of coagulated albumen and foam.